Photographic gelatine layer



i atenteefi UNITED STATES PATENT orrica JGHANNES IBBUNKEN, OF DESSAU .IN ANHALT, GERMANY, ASSIGNOR TO A G'FA ANSCO CORPORATION, OF BINGHAMTON, NEW YORK, A CORPORATION OF NEW YORK PHO'1OGRAIE'IHIG GELATINE LAYEE No Drawing. Application filed July 7, 1931, Serial No. 549,331,- and in Germany July 11, 1930.

The present invention relates to an improvement in the manufacture of photographic materials and more particularly to a process of hardening the gelatinous emulsion layers on photographic films, plates or papers.

Another object of the invention are the new photographic materials provided with a gelatine layer prepared according to the in- 1 vention.

It is known to harden gelatinous emulsion layers by means of formaline or acrolein. The layers t ,us hardened, however, show a very annoying afterhardening. The melting point of a silver halide gelatine emulsion hardened by means of formaline raises, for instance, from 35 C. to 72 C. after a two days storage at 50 C.

According to this invention the afterhardenin can considerably be reduced by using dial ehydes as hardening agents for photographic gelatine emulsions. The reaction of dialdehydes with the gelatine obviously occurs at aconsiderably higher speed. Thus,

2 'for instance,the melting point of a gelatine layer hardened by means of a dialdehyde' raises, after a two days storage at 50 C., only from 37 C. to 42 (3., and even after a ten days storage at this temperature it onlyv 80 raises to 49 C. Consequently, it is possible,

when making use of the dialdehydes, to impart to the said gelatine layer a hardness that remains rather constant. 7

Moreover, the dialdehydes have, as compared with formaline andacrolein, the further advantage of exerting a stronger hardening\ action, when comparing equivalent quantiti'es.

Also when compared with the metal salts, for instance of aluminium or chromium, known to be hardening agents for albuminous substances the dialdehydes involve an advantage inasmuch as the hardness obtained by their action remains constant in the alkaline developer and is not reduced, as it is the case with the said metal salts, by the action of the alkali.

Dialdehydes suitable according to this invention are for instance, glyoxal and mesoxaldialdehy e. Both the monomeric and the polymeric forms are suited, with the difierence that the latter have a somewhat smaller hardening action. The hardening process may be carried out in the same way as with formaldehyde, either by adding the hardening agent to a solution of the gelatine or by subsequently bathing the shaped and dried albuminous bodies in a solution of the hardening agent. 1

The following examples illustrate the invention:

(1) 500 grams of a photographic gelatine emulsion containing 8-10 per cent. of gelatine, comprising a'silver halide, and melting when dry at 32 0., are mixed at 35 C. with 4 cc. of a 1 per cent. aqueous solution of monomeric glyoxal or 5 cc. of a 1 per cent. solution of p-glyoxal and poured in the usual manner on glass lates or films. After drying the layer s ows a melting point of "'periments should be made to determine the best kind of dialdehyde and the most suitable amount to employ with a particular gelatine which is to be hardened to a desired degree.

As well known a peculiar hardening of gelatinous layers is necessary when exportin hotographic materials into the tropics.

hat I claim is:

1. In the manufacture of photographic articles provided with a gelatine emulsion layer of constant hardness the step which comprises acting upon the said gelatine emulsion with a dilute solution of an aliphatic dialdehyde.

2. In the manufacture of photographic articles provided with a gelatine emulsion layer of constant hardness the step which 1 comprises acting, upon the said gelatine emulsion with a ute solution of glyoxal.

3. In the manufacture of articles provided with a gelatme emulsion layer of constant hardness the step which comprises acting upon the said gelatine emulsion with-a dilute solutionof polymerized glyoxal.

4. In the manufacture of photographic articles provided with a gelatlne emulsion layer of constant hardness the step which comprises actin upon the said gelatine emulsion with a ilute solution of mesoxaldialdehyde.

5. Photographic materials provided with a gelatine silver halide emulsion layer, said gelatine layer containing the condensation. product of gelatine with an aliphatic dialdehyde.

6. Photographic materials provided with a gelatine silver halideemulsion'layer, said gelatine layer containing the condensation product of gelatine with glyoxal.

7. Photographic materials provided with a gelatine silver halide emulsion layer, said gelatine la er containing the condensation pfoduclt 0g gelatine with a polymerized g yoxa 8. Photographic materials provided with a gelatine silver halide emulsion layer, said gelatine layer containing the condensation product ofgelatine with mesoxaldialdehyde.

In testimony whereof, I afiix my signature.

JOHANNES BRUNKEN.

photographic 

